Approaching head-on & magnetic flight level (360/180°)

[177]

The Rules stаte... "When two aircraft are apprоaching head-on or approximately so, both should yield to the right."

But what if they're slightly оff to the right of each other? Is it still a gооd idea to turn right?

https://i.imgur.com/Zr6vz1I.jpg

How to deal with a situation when yоu need to fly directly southbound (180° mag track) or northbound (360°)? It's impossible to keep a constant track of 360/180° and yоu will be off-course by +/-1° anyway flying in that direction.

https://i.imgur.com/ilHdj4y.jpg

[The Ancient Geek]

Turn right.
"approaching head on or approximately so"
The rule is simple - always go right.

[177]

The second question is about which FL do you need to stick with when you have to fly directly south or north

[inbalance]

The second question is about which FL do you need to stick with when you have to fly directly south or north
It’s all written in the book.
000 till 179 = odd
180 till 359 = even

[Fl1ingfrog]

But what if they're slightly оff to the right of each other? Is it still a gооd idea to turn right?

Apply the rule of common sense. If its as you describe switch on the landing lights and change course to the right keeping the oncoming aircraft safely on the left.

How to deal with a situation when yоu need to fly directly southbound (180° mag track) or northbound (360°)? It's impossible to keep a constant track of 360/180° and yоu will be off-course by +/-1° anyway flying in that direction.

No pilot can keep a constant track to one or two degrees. An airway, by example, has a minimum width of 10 NM and this allows for a track error of up to +/- 10 degrees, the mean track being the centre line. The semi-circular rule is a flight planning matter only and with reference to the intended magnetic track. Once in flight then do your best. A track error of up to 10 degrees is reasonable. Off track errors should be corrected using the method you have adopted or been taught. It is expected that the track that you achieve is a mean track and so very unlikely to be constant.

[jmmoric]

No pilot can keep a constant track to one or two degrees. An airway, by example, has a minimum width of 10 NM and this allows for a track error of up to +/- 10 degrees, the mean track being the centre line. The semi-circular rule is a flight planning matter only and with reference to the intended magnetic track. Once in flight then do your best. A track error of up to 10 degrees is reasonable. Off track errors should be corrected using the method you have adopted or been taught. It is expected that the track that you achieve is a mean track and so very unlikely to be constant.

Agreed, and for airways in particular, the even-odd level direction is normally described in the AIP.

[scifi]

The semi circular rule can hardly ever be used in the average spam-can in UK. If you want to fly at FL085, it will take you 20 minutes to climb to that altitude at cruise climb speeds, and a further 20 minutes to descend. So for 80 miles you will be either climbing or descending... For most of UK you can hardly find 80 miles of clear airspace without bumping into controlled airspace. At lower levels your altitude will depend more on terrain and cloud avoidance.

[ex82watcher]

Agreed, and for airways in particular, the even-odd level direction is normally described in the AIP.
And at the end of the day,on Airways,ATC will allocate your level.

[ShyTorque]

The problem shouldn't really occur if ATC are involved; they should ensure altitude separation. The situation referred to by the OP is more likely to occur in Class G and then we have to rely on everyone else doing the right thing with regard to choice of flight level....good luck!

If not, the "book" answer assumes that both pilots are aware of the other's aircraft. From experience this most certainly isn't always the case.

Problem comes if you think it's better to go to your left because you're slightly offset to the left of the other aircraft and at that same time he suddenly spots you and breaks hard to his right....you're then on a collision course and you're also in the wrong.

The trick is deciding when you're absolutely head on, or not. Sometimes you look close but are not actually on a collision course and it might then be better to continue straight ahead, or change altitude slightly to avoid. As usual though, in aviation, there isn't a one size fits all answer.

[jmmoric]

And at the end of the day,on Airways,ATC will allocate your level.

We definately will ;)

The problem shouldn't really occur if ATC are involved; they should ensure altitude separation. The situation referred to by the OP is more likely to occur in Class G and then we have to rely on everyone else doing the right thing with regard to choice of flight level....good luck!

Shall ensure (just to be a bitch about the choice of words), we do share boundary with class G, so in or case we'll always try to hand them off in the correct altitude, unless terrain or traffic is a hindrance ofcourse.

[Fl1ingfrog]

The trick is deciding when you're absolutely head on, or not. Sometimes you look close but are not actually on a collision course .................. As usual though, in aviation, there isn't a one size fits all answer.

The design of an Aircraft's navigation (position) lights are with this in mind. You cannot simply look along the nose (avoiding parallax) because the heading is not the track made good: e.g. off setting for drift by +/- 15 degrees is not unusual. The RED-GREEN-WHITE arrangement of lights should be understood. However, other than strobes navigation lights will not be easy to see during daylight. The basic rule is: 'a constant bearing indicates a a collision course and therefore should be treated so.

[ShyTorque]

The design of an Aircraft's navigation (position) lights are with this in mind. You cannot simply look along the nose (avoiding parallax) because the heading is not the track made good: e.g. off setting for drift by +/- 15 degrees is not unusual. The RED-GREEN-WHITE arrangement of lights should be understood. However, other than strobes navigation lights will not be easy to see during daylight. The basic rule is: 'a constant bearing indicates a a collision course and therefore should be treated so.

Correct and of course there is no obligation to display navigation lights by day. Regarding the constant bearing rule, everyone should know that - every pilot flying solo will have already passed the Air Law exam. The question of last minute collision avoidance shouldn't occur if everyone looked out properly. Unfortunately, there's no getting away from the fact that some pilots operating in Class G have relatively poor lookout, relatively low situational awareness and still for some, a reluctance to use the aircraft's transponder to help others become aware of them in good time.

[jmmoric]

I wholeheartedly agree.

Always try having my passengers helping by looking out.

For some reason the controlzones and TMA's is the place where I relax when it comes to looking out, knowing ATC will provide traffic information if relevant, stressing a bit more about it just outside controlled airspaces around airports. where the density of VFR traffic is higher, and everyone are converging/diverging from the airport, tuning their radioes etc.

[Jim59]

Quote:
Originally Posted by 177 View Post (https://www.pprune.org/private-flying/639774-approaching-head-magnetic-flight-level-360-180-a.html#post11025115)
The second question is about which FL do you need to stick with when you have to fly directly south or north
It’s all written in the book.
000 till 179 = odd
180 till 359 = even

The book isn't that simple
000 till 179 IFR odd (starting at 1000')
000 till 179 VFR odd + 500 (starting at 3500')
180 till 359 IFR even (starting at 2000')
180 till 359 VFR even + 500 (starting at 4500')

[jmmoric]

The book isn't that simple
000 till 179 IFR odd (starting at 1000')
000 till 179 VFR odd + 500 (starting at 3500')
180 till 359 IFR even (starting at 2000')
180 till 359 VFR even + 500 (starting at 4500')

The rule for VFR applies only when flying at more than 3000FT AMSL or AGL.

[rolling20]

A few years ago, whilst accepting a flight information service in an airfield zone, heading roughly 180, I had an aircraft approaching approximately the same height and reciprocal heading.
​​​​​​
The occupant didn't see me.
There was no time to turn right ( had I done so, I am convinced it would have hit me).
I shoved the nose down and firewalled it. I felt the prop wash as it flew over, or something similar.
I radioed the FI service, they were not aware of the other aircraft.
My passenger, head down hit the ceiling, we both got covered in dust that flew up from the cockpit floor.
It was over in seconds, my natural reaction was to dive.
Perhaps it was lucky the other aircraft hadn't seen me, the outcome might have been different.